For just a fraction of a second, researchers from the University of Southampton observed violent red flashes stemming from one of the brightest black hole outbursts seen in recent years. The black hole, V404 Cygni, underwent a significant brightening back in June 2015, which lasted approximately two weeks. It was the first black hole identified in the Milky Way and when it feasts on material, it can reach very high levels of brightness.
A new study continues to explore this unique brightness, reporting red flashes - likely from fast-moving jets of matter - that took place when the black hole spit out material that it was unable to swallow. The new findings shed light on the formation of these jets and the extreme phenomena that can take place during the process of a black hole engulfing matter.
"The very high speed tells us that the region where this red light is being emitted must be very compact," said Poshak Gandhi, lead author of the study. "Piecing together clues about the color, speed, and the power of these flashes, we conclude that this light is being emitted from the base of the black hole jet. The origin of these jets is still unknown, although strong magnetic fields are suspected to play a role."
Gandhi added that the red flashes occurred during the height of the black hole's feeding, leading the team to believe that they originate from the black hole spitting out material during the process of being rapidly force-fed an orbiting star.
The team reports that each flash was equivalent to the power output of 1,000 suns, taking place in time intervals approximately 10 times faster than the blink of an eye.
These kinds of black hole outbursts are not only rare, they are very unpredictable, making them hard to catch. In the current study, the observations were made using the novel ULTRACAM fast imaging camera, which is mounted on the William Herschel Telescope in La Palma on the Canary Islands.
"ULTRACAM is unique in that it can operate at very high speed, capturing high frame-rate 'movies' of astronomical targets, in three colors simultaneously," said Vik Dhillon, co-creator of the device. "This allowed us to ascertain the red color of these flashes of light from V404 Cygni."
The findings were published in the March 14 issue of the Monthly Notices of the Royal Astronomical Society.
